/*

 https://github.com/superwills/NibbleAndAHalf
 base64.h -- Fast base64 encoding and decoding.
 version 1.0.0, April 17, 2013 143a

 Copyright (C) 2013 William Sherif

 This software is provided 'as-is', without any express or implied
 warranty.  In no event will the authors be held liable for any damages
 arising from the use of this software.

 Permission is granted to anyone to use this software for any purpose,
 including commercial applications, and to alter it and redistribute it
 freely, subject to the following restrictions:

 1. The origin of this software must not be misrepresented; you must not
 claim that you wrote the original software. If you use this software
 in a product, an acknowledgment in the product documentation would be
 appreciated but is not required.
 2. Altered source versions must be plainly marked as such, and must not be
 misrepresented as being the original software.
 3. This notice may not be removed or altered from any source distribution.

 William Sherif
 will.sherif@gmail.com

 YWxsIHlvdXIgYmFzZSBhcmUgYmVsb25nIHRvIHVz

 */
#ifndef BASE64_H
#define BASE64_H

#include <stdio.h>
#include <stdlib.h>

#include "../EngiLicenseManagerGlobal.h"

const static char* b64 =
		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

// maps A=>0,B=>1..
const static unsigned char unb64[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //10
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //20
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //30
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //40
		0, 0, 0, 62, 0, 0, 0, 63, 52, 53, //50
		54, 55, 56, 57, 58, 59, 60, 61, 0, 0, //60
		0, 0, 0, 0, 0, 0, 1, 2, 3, 4, //70
		5, 6, 7, 8, 9, 10, 11, 12, 13, 14, //80
		15, 16, 17, 18, 19, 20, 21, 22, 23, 24, //90
		25, 0, 0, 0, 0, 0, 0, 26, 27, 28, //100
		29, 30, 31, 32, 33, 34, 35, 36, 37, 38, //110
		39, 40, 41, 42, 43, 44, 45, 46, 47, 48, //120
		49, 50, 51, 0, 0, 0, 0, 0, 0, 0, //130
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //140
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //150
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //160
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //170
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //180
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //190
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //200
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //210
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //220
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //230
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //240
		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //250
		0, 0, 0, 0, 0, 0, }; // This array has 255 elements

// Converts binary data of length=len to base64 characters.
// Length of the resultant string is stored in flen
// (you must pass pointer flen).
char* base64(const void* binaryData, int len, int *flen) {
	const unsigned char* bin = (const unsigned char*) binaryData;
	char* res;

	int rc = 0; // result counter
	int byteNo; // I need this after the loop

	int modulusLen = len % 3;
	int pad = ((modulusLen & 1) << 1) + ((modulusLen & 2) >> 1); // 2 gives 1 and 1 gives 2, but 0 gives 0.

	*flen = 4 * (len + pad) / 3;
	res = (char*) malloc(*flen + 1); // and one for the null
	if (!res) {
		puts("ERROR: base64 could not allocate enough memory.");
		puts("I must stop because I could not get enough");
		return 0;
	}

	for (byteNo = 0; byteNo <= len - 3; byteNo += 3) {
		unsigned char BYTE0 = bin[byteNo];
		unsigned char BYTE1 = bin[byteNo + 1];
		unsigned char BYTE2 = bin[byteNo + 2];
		res[rc++] = b64[BYTE0 >> 2];
		res[rc++] = b64[((0x3 & BYTE0) << 4) + (BYTE1 >> 4)];
		res[rc++] = b64[((0x0f & BYTE1) << 2) + (BYTE2 >> 6)];
		res[rc++] = b64[0x3f & BYTE2];
	}

	if (pad == 2) {
		res[rc++] = b64[bin[byteNo] >> 2];
		res[rc++] = b64[(0x3 & bin[byteNo]) << 4];
		res[rc++] = '=';
		res[rc++] = '=';
	} else if (pad == 1) {
		res[rc++] = b64[bin[byteNo] >> 2];
		res[rc++] = b64[((0x3 & bin[byteNo]) << 4) + (bin[byteNo + 1] >> 4)];
		res[rc++] = b64[(0x0f & bin[byteNo + 1]) << 2];
		res[rc++] = '=';
	}

	res[rc] = 0; // NULL TERMINATOR! ;)
	return res;
}

unsigned char* unbase64(const char* ascii, int len, int *flen) {
	const unsigned char *safeAsciiPtr = (const unsigned char*) ascii;
	unsigned char *bin;
	int cb = 0;
	int charNo;
	int pad = 0;

	if (len < 2) { // 2 accesses below would be OOB.
		// catch empty string, return NULL as result.
		puts(
				"ERROR: You passed an invalid base64 string (too short). You get NULL back.");
		*flen = 0;
		return 0;
	}
	if (safeAsciiPtr[len - 1] == '=')
		++pad;
	if (safeAsciiPtr[len - 2] == '=')
		++pad;

	*flen = 3 * len / 4 - pad;
	bin = (unsigned char*) malloc(*flen);
	if (!bin) {
		puts("ERROR: unbase64 could not allocate enough memory.");
		puts("I must stop because I could not get enough");
		return 0;
	}

	for (charNo = 0; charNo <= len - 4 - pad; charNo += 4) {
		int A = unb64[safeAsciiPtr[charNo]];
		int B = unb64[safeAsciiPtr[charNo + 1]];
		int C = unb64[safeAsciiPtr[charNo + 2]];
		int D = unb64[safeAsciiPtr[charNo + 3]];

		bin[cb++] = (A << 2) | (B >> 4);
		bin[cb++] = (B << 4) | (C >> 2);
		bin[cb++] = (C << 6) | (D);
	}

	if (pad == 1) {
		int A = unb64[safeAsciiPtr[charNo]];
		int B = unb64[safeAsciiPtr[charNo + 1]];
		int C = unb64[safeAsciiPtr[charNo + 2]];

		bin[cb++] = (A << 2) | (B >> 4);
		bin[cb++] = (B << 4) | (C >> 2);
	} else if (pad == 2) {
		int A = unb64[safeAsciiPtr[charNo]];
		int B = unb64[safeAsciiPtr[charNo + 1]];

		bin[cb++] = (A << 2) | (B >> 4);
	}

	return bin;
}

#endif
